JP2005246548A - Magnetic polishing fluid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic polishing fluid usable for polishing a ceramic material, an optical material and furthermore a metal surface, having excellent polishing characteristics and causing little change in the polishing characteristics by temperature change. <P>SOLUTION: The magnetic polishing fluid contains magnetic grains, abrasive grains, an additive and a medium. The magnetic grains have the average grain diameter of 1-10 μm, and the ratio of the average grain diameter of the abrasive grains to the average grain diameter of the magnetic grains is 0.01 ≤ average grain diameter of abrasive grains / average grain diameter of magnetic grains < 1. The additive is amino-modified silicone oil containing polydimethylsiloxane as a principal chain and containing an amino group as its side chain or end. The medium is silicone oil. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to a magnetic polishing fluid that can be used for polishing ceramic materials, optical materials, and metal surfaces, has excellent polishing characteristics, and has little change in polishing characteristics with respect to temperature change.

It is known to use magnetorheological fluids for polishing and polishing ceramic, optical and metallic substrates.
A description of a liquid composition called a magnetorheological fluid or a magnetorheological material that changes its fluid properties in response to a magnetic field is described in the non-patent document described in “Properties of Magnetic Fluid (issued in February 1955)” by AIEE Transactions. As seen in Document 1, Patent Document 1 discloses a magnetorheological fluid containing iron oleate or the like as a dispersant, and other techniques are disclosed in Patent Document 2, Patent Document 3, Patent Document 4, Patent Document 5, and the like. Is disclosed. In any of these magnetorheological fluids, the contained magnetic particles (average particle size: several tens of nanometers to several tens of micrometers) are aligned by an externally applied magnetic field to form chain clusters, thereby increasing the viscosity or It gels and its flow characteristics and yield stress change significantly.

When abrasive particles are mixed with these known magnetorheological fluids, solid characteristics are imparted by an increase in the viscosity of the fluid when a magnetic field is applied to the fluid, and suitable characteristics for polishing can be exhibited. Patent Document 6 discloses a magnetic polishing fluid composition suitable for polishing ceramic and glass substrates.

Normally, when magnetic polishing fluid is used, the temperature rise is inevitable because frictional heat is generated at the polishing site. As a result, the composition ratio changes due to the volatilization of the solvent, the solvent viscosity decreases, and the viscosity of the fluid is remarkably high. There was a problem that the polishing characteristics changed significantly. For this reason, the problem has been avoided by using a cooling device for avoiding a rise in temperature, but it is difficult to apply to a member that needs to be polished at a relatively high temperature such as a metal surface. The problem remained.

US Pat. No. 2,661,596 US Patent No. 3006656 US Pat. No. 4,604,229 Japanese Patent Laid-Open No. 51-13995 JP 51-44579 A JP-T-2002-544318 J. et al. D. Coolidge Jr. & R. W. Article 55-170 (p.149-152) by Harberg

In view of the above situation, the present invention provides a magnetic polishing fluid that can be used for polishing ceramic materials, optical materials, and even metal surfaces, has excellent polishing characteristics, and has little change in polishing characteristics with respect to temperature changes. It is intended.

The inventor defines a ratio of the abrasive particle diameter / magnetic particle diameter, and further uses a specific medium and additive to complete a magnetic polishing fluid whose polishing characteristics hardly change even with a significant temperature change. It came.
That is, the present invention is a magnetic polishing fluid containing magnetic particles, abrasive particles, additives and a medium, wherein the magnetic particles have an average particle size of 1 to 10 μm, the average particle size of the abrasive particles and the above The ratio of the average particle diameter of the magnetic particles is 0.01 ≦ average particle diameter of abrasive particles / average particle diameter of magnetic particles <1, and the additive has polydimethylsiloxane as a main chain and its side chain or terminal. The amino-modified silicone oil contains an amino group, and the medium is a magnetic polishing fluid that is a silicone oil.

The magnetic polishing fluid of the present invention contains magnetic particles, polishing particles, additives and a medium.
The magnetic particles used in the present invention are not particularly limited as long as they have magnetism. For example, iron, iron nitride, iron carbide, carbonyl iron, chromium dioxide, low carbon steel, nickel, cobalt; aluminum-containing iron alloy Iron alloys such as silicon-containing iron alloys, cobalt-containing iron alloys, nickel-containing iron alloys, vanadium-containing iron alloys, molybdenum-containing iron alloys, chromium-containing iron alloys, tungsten-containing iron alloys, manganese-containing iron alloys, copper-containing iron alloys; The particle | grains which consist of these mixtures etc. can be mentioned.

The average particle size of the magnetic particles needs to be 1 to 10 μm. If the average particle size of the magnetic particles is less than 1 μm, the particle size is too small to expect a significant increase in viscosity when a magnetic field is applied. It is difficult to retain the magnetic particles therein, the fluid becomes very heterogeneous, and the polishing characteristics change.

The blending amount of the magnetic particles is preferably 10 to 90% by weight with respect to the entire magnetic polishing fluid. When the amount is less than 10% by weight, the increase in viscosity of the obtained magnetic polishing fluid when a magnetic field is applied is small, and when it exceeds 90% by weight, the fluidity of the magnetic polishing fluid may be lowered. More preferably, the lower limit is 50% by weight and the upper limit is 85% by weight.

As said magnetic particle, you may use what was processed by the silane coupling agent which has an epoxy group or an amino group. By treating the magnetic particles with a silane coupling agent having an epoxy group or an amino group, the dispersion stability is much superior to untreated magnetic particles.

The silane coupling agent is represented by the following general formula (1).
X- (Y) -SiR _3-b L _b (1)
In the formula, X represents an epoxy group, a cyclic epoxy group or an amino group; Y represents a hydrocarbon group containing (CH ₂ ) _k , an ether bond, an ester bond or a ketone bond; R represents a methyl group, an ethyl group or a propyl group Group, alkyl group such as butyl group, halogen atom, hydroxyl group, methoxy group, ethoxy group, propoxy group, butoxy group and other alkoxy groups, or formyl group, acetoxy group, pyropionyloxy group, butyryloxy group and other acyloxy groups B represents an integer of 1 to 3;

As a method of treating the magnetic particles with a silane coupling agent having an epoxy group or an amino group, for example, in a solution in which the silane coupling agent containing the epoxy group or amino group is dissolved in a solvent such as alcohol, By immersing the magnetic particles or spraying the silane coupling agent solution onto the magnetic particles and then volatilizing the solvent. Furthermore, after volatilizing the solvent, a heat treatment may be performed at 40 to 150 ° C. for 5 minutes to 24 hours.

The abrasive particles used in the present invention are not particularly limited, and known materials can be used. For example, α-Fe ₂ O ₃ , ThO ₂ , ZrO ₂ , SnO ₂ , CeO ₂ , SiO ₂ , Al _{2 can be used.} Examples thereof include oxides such as O ₃ and ZnO; SiC and polycrystalline diamond particles.

The ratio of the average particle size of the abrasive particles to the average particle size of the magnetic particles needs to be 0.01 ≦ average particle size of abrasive particles / average particle size of magnetic particles <1. If the “average particle size of the abrasive particles / average particle size of the magnetic particles” is less than 0.01, the surface area of the abrasive particles with respect to the magnetic particles is too small, and the processability is inferior. Thus, the abrasive particles are large, and the abrasive particles cannot be sufficiently retained due to the increase in viscosity due to the magnetic particles, and good polishing characteristics cannot be obtained.

The blending amount of the abrasive particles is preferably 0.1 to 20% by weight with respect to the entire magnetic polishing fluid. If it is less than 0.1% by weight, sufficient polishing characteristics cannot be obtained, and if it exceeds 20% by weight, the fluidity of the magnetic polishing fluid may be lowered. More preferably, the lower limit is 0.5% by weight and the upper limit is 10% by weight.

The magnetic polishing fluid of the present invention requires the use of amino-modified silicone oil as an additive. By blending amino-modified silicone oil as an additive, the magnetic particles can be stably dispersed.
The amino-modified silicone oil used in the present invention contains polydimethylsiloxane represented by the following general formula (2) as a main chain and contains an amino group in the side chain or terminal.

In the formula, at least one of R ¹ , R ² and R ³ represents Y—NH ₂ , and the other represents a methyl group. Y represents a hydrocarbon group containing (CH ₂ ) _k , an ether bond, an ester bond or a ketone bond.
As the amino-modified silicone oil used in the present invention, instead of using an amino-modified polydimethylsiloxane containing the polydimethylsiloxane represented by the general formula (2) as a main chain and having an amino group in its side chain, phenylsiloxane or the like When an amino-modified silicone oil having a skeleton is used, amino groups cannot be effectively adsorbed on the magnetic particles due to steric hindrance due to phenyl groups or the like, and excellent dispersion stability cannot be obtained.

In addition, when carboxyl-modified polydimethylsiloxane or alcohol-modified polydimethylpolysiloxane is used instead of the amino-modified polydimethylsiloxane, the compatibility with the magnetic particles is poor and stable dispersibility cannot be obtained.
The amino-modified silicone oil used in the present invention is particularly preferably one having polydimethylsiloxane as the main chain and containing an amino group in the side chain.

The medium (carrier fluid) used in the present invention is silicone oil, and specifically, polydimethylsiloxane in which R ¹ , R ² and R ^{3 in the} general formula (2) are all methyl groups.
The viscosity of the silicone oil is preferably 10 to 1000 cps at 25 ° C. When the viscosity is less than 10 cps, the boiling point is low, so when the viscosity increases significantly, the composition changes due to the volatilization of the solvent. When the viscosity exceeds 1000 cps, the viscosity is too high, the fluidity is deteriorated, and good polishing characteristics are obtained. Cannot be obtained. More preferably, the lower limit is 10 cps and the upper limit is 100 cps.
Moreover, as said silicone oil, a thing with little change in the viscosity in 25 degreeC and the viscosity in 120 degreeC is preferable. A temperature increase due to generation of frictional heat is unavoidable at the polishing portion, and the temperature rises to about 120 ° C. If the viscosity does not change due to a temperature change, stable polishing can be performed.

The magnetic polishing fluid of the present invention has an antioxidant, an anti-aging agent or other stabilizer, an antiseptic, a viscosity modifier, a flame retardant, a surfactant, etc. These additives can be used in combination.
As a method for producing the magnetorheological fluid of the present invention, the material is first put into a container, premixed with a spatula or the like, and then mixed with a disperser such as a homogenizer, a ball mill, a sand mill, or a three roll.

According to the present invention, the ratio of the abrasive particle diameter / magnetic particle diameter is defined, and furthermore, by using a specific medium and additive, the polishing characteristics are excellent, and the magnetic characteristics in which the polishing characteristics hardly change with temperature change. A polishing fluid can be obtained.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples.

(Examples 1-3 and Comparative Examples 1-4)
1. Preparation of magnetic polishing fluid (1) Preparation of magnetic particles 100 parts by weight of carbonyl iron powder (carbonyl iron powder CM, manufactured by BASF), 2 parts by weight of silane monomer (A-1100, manufactured by Nihon Unicar) and 48 parts by weight of methanol It was immersed in the solution which consists of and left at room temperature until methanol evaporated. Then, it heated at 110 degreeC for 30 minutes.
(2) Production of Magnetorheological Fluid Each magnetic polishing fluid was prepared according to the formulation shown in Table 1 below.

Each material described in Table 1 is as follows.
1) BASF particle size 5μm
2) Magnetic particles prepared in (1) 5 μm
3) Titanium Industry Co., Ltd. 0.3μm
4) Alumina particles Fujimi Incorporated, particle size 0.6μm
5) Alumina particles Fujimi Incorporated, particle size 5.5 μm
6) Nihon Unicar 10cSt
7) Prototype 8000mm ² / s
8) 1000mm ² / s made by Nippon Unicar Company
9) Nippon Unicar Co., Ltd. 1000mm ² / s
10) Special reagent grade 10% aqueous solution

100 ml of a premixed mixture of the above materials was put into a pot having an inner diameter of 90 mm and a capacity of 450 ml, and a 1 / 4-inch steel ball 1000 g was added and rotated on a ball mill rotary table for 100 rpm * 24 hours to prepare a magnetic polishing fluid.

2. Evaluation Method Using the polishing apparatus shown in FIG. 1, a magnetic polishing fluid is poured into a pipe made of material SUS304 and having an outer diameter of 20 mm and an inner diameter of 18 mm, and magnetic poles (permanent magnets) are arranged at four equal locations between the outer diameters of the pipe. The pipe was rotated at 1800 rpm with magnetism applied, the inner surface of the pipe was polished with a magnetic polishing fluid, and the polishing characteristics of the magnetic polishing fluid were measured. The magnetic flux density of the magnetic pole (permanent magnet) was 4000 G, and processing was performed under the conditions of amplitude ± 5 mm, frequency 0.8 Hz, and time 15 min. The temperature at the start of polishing was 22 ° C.

3. Evaluation item (1) Polishing amount The polishing amount was calculated from the weight reduction of the substrate before and after the polishing treatment.
(2) Surface roughness The surface roughness (Rz) of the substrate before and after the polishing treatment was measured using a surface roughness meter.
4). Evaluation results

Since the present invention has the above-described configuration, it is possible to obtain a magnetorheological fluid whose polishing characteristics hardly change even when the temperature changes significantly.

It is a figure which shows the outline | summary of the grinding | polishing apparatus used for evaluation in an Example.

Explanation of symbols

1 Chuck 2 Workpiece (SUS pipe)
3 Magnetic pole holder 4 Vibration source 5 Slide table 6 Magnetic pole 7 Magnetic polishing fluid 8 Rail

Claims (3)

A magnetic polishing fluid containing magnetic particles, abrasive particles, additives and media,
The magnetic particles have an average particle diameter of 1 to 10 μm,
The ratio of the average particle size of the abrasive particles to the average particle size of the magnetic particles is 0.01 ≦ average particle size of abrasive particles / average particle size of magnetic particles <1.
The additive is an amino-modified silicone oil having polydimethylsiloxane as a main chain and containing an amino group at a side chain or a terminal,
The magnetic polishing fluid, wherein the medium is silicone oil. 2. The magnetic polishing fluid according to claim 1, wherein the amino-modified silicone oil contains polydimethylsiloxane as a main chain and an amino group in its side chain. 3. The magnetic polishing fluid according to claim 1, wherein the magnetic particles are treated with a silane coupling agent having an epoxy group or an amino group.

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